Hydraulic Turbine Power Generator incorporating a plurality of Reaction type turbine stages including a turbine stage with adjustable blades for maximizing turbine efficiency and controlling the output electrical frequency of the power generator.
This invention is an improvement of the Hydraulic Turbine Power Generator that is the subject of the Weisser U.S. Pat. No. 5,659,205, assigned to the same assignee as the present invention. The hydraulic turbine of U.S. Pat. No. 5,659,205 is operable with a hydraulic fluid source that has a variable flow rate and a high pressure and is converted by the turbine structure to a relatively high fluid velocity. The turbine runner blades disclosed in the prior patent are fixed, axial runner blades so that the rotary speeds imparted to the single shaft mounting the hydraulic turbine and power generator is operative at variable, rotary speeds. The power generator is provided with a variable frequency exciting current source controlling the synchronous speed of the generator to be changed by connecting the power generator stator windings to be energized by the variable frequency exciting current source thereby providing output power at a preselected, constant frequency to compensate for the variable output frequencies generated in response to the variable shaft speeds of the single shaft mounting the power generator. Experience with the patented hydraulic power generator has resulted in that the need for the variable speed, constant frequency controller, identified in the above identified prior patent as element IS, has produced problems due to the operational problems encountered with the commercially available controller IS. This problem has resulted in the desirability of providing a hydraulic turbine power generator and more particularly submersible hydraulic turbine power generator operative with preselected hydraulic fluids that eliminate the need for the use of the variable speed, constant frequency controller to thereby provide a power generator free of the frequency controller problems.
The present invention provides an improved hydraulic turbine power generator arranged on a single shaft that is operable as a submersible hydraulic turbine electrical power generator that is operative at a constant speed and provides output power at a constant frequency without the need for a variable speed, constant frequency controller for the power generated resulting in a relatively trouble free hydraulic turbine electrical power generator.
The basic concept of the present invention is the incorporation of a plurality of reaction type turbine stages arranged in serial fashion on the single shaft for the hydraulic turbine power generator with the output stage of the hydraulic turbine being responsive to the fluid flow discharged from the input turbine stage or stages and being characterized as having a plurality of adjustable blades that permit the pitch of the blades to be adjusted for varying the fluid flow through the output stage to achieve a substantially constant speed for the single shaft mounting the hydraulic turbine and electrical power generator and maximizing the efficiency of the turbine. The input turbine can be a Francis type turbine stage of single or a plurality of stages while the output turbine stage can be a Kaplan type turbine stage.
In accordance with the present invention the adjustable pitch blades can be rotated to any desired position by either statically moving the blades when the turbine is inoperative or by dynamically adjusting the turbine blades when the turbine is operative. In the disclosed static adjustment of the adjustable turbine vanes, the hydraulic turbine mounts a supporting structure adjacent the fluid discharge end thereof for mounting an electrical motorized device operable to extend a keyed blade for adjustment purposes. A gear drive system is imbedded into Kaplan style turbine runner for controlling the pitch of the runner blades of the Kaplan style turbine runner so that the efficiency of the turbine can be fine tuned. The keyed blade is adapted to fit into a positioning shaft controlling the movements of the gear drive system. This static adjustment is accomplished while the turbine is inoperable and when the adjustment is complete, the keyed blade is retracted and the turbine is in condition to be operated at the adjusted pitch for the runner blades.
The dynamic adjustment of the Kaplan style runner blades is accomplished while the turbine is operative by the use of a gear drive system imbedded into the Kaplan style runners also controlled by a positioning shaft. In this case, a low voltage stepper motor incrementally controls the positioning shaft and thereby the pitch of the runner blades with the turbine in operation. The stepper motor is powered from the turbine electrical power generator by tapping off the rotor end rings and with the stepper motor being responsive to digital positioning commands. The power flow in the rotor is low voltage and low frequency of approximately 20 Hertz while the digital signals are transmitted to the stepping motor through the turbine electrical power generator rotor by means of the magnetic field across the gap between the rotor and stator of the power generator.
The use of the turbine with adjustable blades is also advantageous when the source of hydraulic fluid is in two phases, namely a liquid and gas/vapor mixture. In this embodiment, a turbine expander is used for permitting pressure reduction into the vapor phase but takes advantage of the buoyant and convective forces of released gas or vapor by routing the fluid in a vertical direction such that the fluid is aided by these forces as contrasted with the reverse or downward, conventional flow. The reverse fluid flow mixture through the turbine causes the rise of the bubbles of released gas or vaporized liquid aids the primary fluid flow. The entire hydraulic turbine electrical power generator is arranged in a closed container with suitable fluid inlet and a separate fluid outlet and gas/vapor outlet so as to function as a separator of the gas/vapor from the liquid.